Closely related to pufferfish (family Tetraodontidae), the Rounded porcupinefish is one of the smaller
of around 20 porcupinefish species (family Diodontidae), growing to only about seven or eight
inches. The large eyes are well-adapted for night vision, when this
species is most likely to be encountered. If threatened, this fish
inflates itself by gulping water until it gradually becomes spherical in
shape, completely rigid with its large, stiff spines pointed outward to
prevent swallowing by potential predators. In addition to forcing the
spines to point outward, the inflation of its body presents a larger
appearance to help discourage predators.